Mobile phones often send text messages by themselves. What happened? How to set it?

Mobile phones often send messages themselves to see if you have the function of touching the bright screen. Sometimes if this function is set, the phone will automatically light up the screen as long as it has a body temperature. At this time, if a friend sends you a message, the body temperature will touch the keyboard and type some garbled codes. Sometimes the body temperature accidentally touches the send button, and the garbled code will be sent out.